The present invention relates to an image processing apparatus that compresses and encodes an image obtained from an image pickup device and distributes the image, and more particularly to an image processing apparatus that efficiently compresses and encodes an image.
Recently, more and more cameras process megapixels of images. For example, in a network-based surveillance system where images/videos shot by a surveillance camera are transmitted from a transmitter to a receiver (client side) via a transmission line (network) for remotely monitoring a specific object, high-definition, high-quality videos are required. Therefore, more and more megapixel cameras will be used in a surveillance system in future. A typical megapixel image is an SXGA (Super eXtended Graphics Array) image. The SXGA, with a resolution of 1280×1024 pixels, has high definition resolution about four times higher than that of the VGA (Video Graphics Array), 640×480 pixels, generally used in a surveillance system. The problems with the SXGA are as follows. (1) The mainstream display for displaying monitored videos on the client side is an XGA (extended Graphics Array) display with a resolution of 1024×768 pixels. (2) Because the client side must control the camera side (for example, control the camera platform) in the surveillance system, the surveillance videos and the control screen (menu bar, etc.,) must always be displayed on the display screen at the same time. In view of the above, it is difficult to display the whole screen of a megapixel image on the display without losing the high definition of the image.
Therefore, the function to cut out a part of a megapixel image without losing the high definition of the image and display it in an enlarged format, the so-called electronic Pan Tilt Zoom (PTZ) function, is important in the surveillance system.
Conventionally, an image transmission apparatus is disclosed that cuts out and compresses the data of only a required part of an image for efficient transmission and recording (for example, see JP-A-8-106536).